9492600990 25-7
DECS-150 Modbus
®
Communication
Device Address
Function Code = 10 (hex)
Starting Address Hi
Starting Address Lo
No. of Registers Hi
No. of Registers Lo
CRC Hi Error Check
CRC Lo Error Check
Preset Single Register
A Preset Single Register query message requests a single register to be written. If the query is a
broadcast (device address = 0), no response message is returned.
Note: Only data types INT16, INT8, UINT16, UINT8, and String (not longer than 2 bytes), can be preset
by this function.
Query
Data will cease to be written if any of the following exceptions occur.
• Queries to write to Read Only registers result in an error response with Exception Code of “Illegal
Data Address”.
• A query to write an unallowed value (out of range) to a register results in an error response with
Exception Code of “Illegal Data Value”.
Device Address
Function Code = 06 (hex)
Address Hi
Address Lo
Data Hi
Data Lo
CRC Hi error check
CRC Lo error check
Response
The response message echoes the Query message after the register has been altered.
Data Formats
DECS-150 systems support the following data types:
• Data types mapped to 2 registers
o Unsigned Integer 32 (Uint32)
o Floating Point (Float)
o Strings maximum 4 characters long (String)
• Data types mapped to 1 register
o Unsigned Integer 16 (Uint16)
o Unsigned Integer 8 (Uint8)
o Strings maximum 2 characters long (String)
• Data types mapped to more than 2 registers
o Strings longer than 4 characters (String)
Floating Point Data Format (Float)
The Modbus floating point data format uses two consecutive holding registers to represent a data value.
The first register contains the low-order 16 bits of the following 32-bit format:
• MSB is the sign bit for the floating-point value (0 = positive).
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